The objective is to develop new and effective therapeutic approaches involving immuno-therapy for the treatment of non-resectable malignant disease based on studies in dogs with spontaneous neoplasms. The approach will be conducted as follows: a) to detect tumor associated antigens (TAA) and survey reactivity against such antigens both before and during therapy using several in vitro assays, including lymphocyte blastobenesis, migration inhibitory factor production and 51Cr release. b) to perform allogeneic marrow grafts following total body irradiation (TBI) in order to assess the "adoptive" immunotherapeutic effect of allogeneic marrow. c) to assess the antitumor effect of various immunothera- peutic maneuvers, e.g. infusion of stored, sensitized lymphocytes, administration of killed tumor cells or use of in vitro sensitized marrow or lymphocytes, in conjunction with TIB. Both clinical response and change in in vitro reactivity against TAA will be measured. d) to assess the anti-tumor effect of high dose dimethylmyleran (DMM) in conjunction with autologous marrow rescue in dogs with malignant tumors. The absence of immunosuppression following high dose dimethylmyleran (DMM) in conjunction with autologous marrow rescue in dogs with malignant tumors. The absence of immunosuppression following high dose DMM makes its use in conjunction with immunotherapy particularly attractive. e) to assess the additive effect of immuno- therapeutic maneuvers as discussed above on dogs receiving1) high dose DMM and autologous marrow, and 2) lower, non-lethal doses of DMM as determined by both clinical response and in vitro reactivity against TAA.